The invention is directed to an automated system for applying a fluid to an object. The automated system is used to position a fluid applicator in the proper position with respect to the object on which the fluid is being applied. The automated system also has a mechanism for replacing worn fluid applicator tips on the fluid applicator. The automated system utilizes a compliance mechanism that enhances the ability of the automated system to retain contact with the object. The automated system is easily interfaced with robots or other automated devices such as programmable fluid dispensing systems.
One of the primary applications of the automated system is the automotive glass industry where the fluid applicator is used to apply various fluids to the edge of the windshield, lights, and back window. The automated system will be generally described with regard to this particular automotive application. However, it should be understood that these inventions are also suitable for a wide range of other fluid applications. The automotive glass application is only one use and is not meant to limit the scope of the applications for the inventions.
The invention is particularly adapted for the production of glazing units or window assemblies for automotive vehicles, although it will find utility generally in a great many other fields. Installation of fixed window units in earlier automotive vehicles generally involved manual installation of the glazing unit using suitable mechanical fasteners such as metal clips for securing the unit in the vehicle body, applying sealant around the marginal edges of the glazing unit, and positioning decorative trip strips around the unit to cover the junction between the marginal edges of the glazing unit and the adjacent portions of the vehicle body. Assembly and installation of such units was relatively slow and costly inasmuch as a considerable amount of labor was required. The procedure was not readily adaptable to being speeded up to accommodate increased automobile production line rates, nor was it adapted to being automated.
Efforts to overcome these disadvantages resulted in numerous improved window structures. Thus, unitary window assemblies were developed wherein a sheet of glass was provided with an adjacent peripheral frame, with a casting or gasket of molded material extending between the frame and the peripheral margin of the window to hold the glass sheet within the frame. Fasteners provided at spaced locations along the frame permitted the entire assembly to be guided into position over an appropriate opening in a vehicle and secured to the vehicle as a unit. Such unitary window units reduce the time required and simplify installation in the vehicle opening. However, due to the labor required in manually assembling the frame and gasket on the sheet of glass, the structures are relatively costly.
More recently, in order to eliminate the manual assembly, so-called encapsulated glazing units have been developed wherein individual sheets of glass or laminated glass units are formed with integral frame or gasket members molded and cured in situ by a reaction injection molding (RIM) process. One such process and resulting product is shown and described in U.S. Pat. No. 4,561,625 to Weaver. Such encapsulated glazing units can be fabricated with a minimum of hand labor, and the resulting units can be readily attached to the portions of the vehicle body defining the window openings during assembly of the vehicle.
As described in the aforementioned patent, such encapsulated units are fabricated by disposing a predetermined portion of the marginal periphery of a sheet of transparent material within a mold structure. A polymeric gasket forming material is injected into the mold cavity and cured in situ on the sheet to encapsulate the marginal peripheral edge portion of the sheet. The resulting assembly can then be readily attached to the body portion defining the periphery of a window opening during manufacture and assembly of a vehicle.
Due to the nature of the glass surfaces, it is known that the gasket materials may not form a permanent, long term bond directly to the glass. Thus, they may not maintain adhesion to the glass surface for a length of time consistent with the life of the automobile. Exposure to weather moisture and sunlight, as well as other factors, may cause the gasket material to loosen from the glass with the passage of time, and ultimately to separate entirely from the glass. In order to improve the adherence of the gasket material to the glass and increase the service life of the encapsulated units to an acceptable level, it has been common practice to apply a coating of a liquid primer material to the affected surface of the glass prior to formation of the gasket thereon. Heretofore, this has been accomplished as by manually painting a band of the primer material along the appropriate edge portion of the glass panel. Such prior art procedures may, for example, utilize a brush periodically dipped in a container of the primer material, or a plastic squeeze bottle containing the primer material and having a suitable dispensing dober. In any event, the procedures are not entirely satisfactory in that they are time-consuming, labor-intensive and may not result in a satisfactory coating of the primer material. Thus the primer layer, which is generally a urethane material, should be applied as a uniform, continuous, relatively thin band in order to function properly. Should the layer be of excessive thickness, it may separate within the layer along a cleavage plane, resulting in failure of the bond. Of course, if the layer is not of sufficient thickness or if certain areas are not coated, the primer layer would likewise be ineffective for its intended purpose. The primer, and particularly the solvent therefore, may be toxic in nature so that manual application thereof, particularly when using an open container of the primer, may require use of protective equipment by the workers. Such manual application processes also generally result in waste of the primer material and generally messy conditions in the work place. Due to the difficulty in controlling the width of manually applied bands, it may also be necessary to mask the work piece prior to application of the primer material.
Thus, as will be readily apparent, the existing procedures for applying primer material to the edges of sheet material are not entirely satisfactory, and there is a need for a system for efficiently applying a band of primer of a desired uniform thickness and width to such sheet material.
This invention consists of a modular workstation that is interfaced with a programmed robot to apply a liquid to a product, primarily glass, in a precision pattern, utilizing specialized and unique flow applicator tips. Some of the applicator tip designs have been documented in U.S. Pat. No. 5,131,349.
In accordance with the present invention, there is provided a system for applying a uniform band of primer composition along selected portions of the peripheral margin of sheet material such as glazing units of the like. The band may be applied to either or both marginal surfaces, as well as to the edge portion and to interior marginal surfaces of spaced adjacent sheets where desired. The invention has particular utility in applying such bands of primer composition to the marginal edges of glazing unit upon which a plastic frame or gasket member is to be molded in place. However, as will be readily appreciated, it may as well be utilized for application of bands of liquid material in general to any suitable marginal surface.
A family of interchangeable applicator tips is provided for use with a dispenser adapted to provide an on-demand supply of primer compound to the tip in use. The different applicator tips of the family have configurations particularly adapted to applying bands of primer compound along selected peripheral margins of a sheet member, and each is of composite construction including a relatively rigid base member to which is bonded a soft wicking and absorbent body for contacting and transferring to the sheet surface the layer of primer compound. The tips are readily attachable to and removable from a fluid dispenser or other dispensing unit providing a supply of the primer compound. The fluid dispenser, or a plurality of the fluid dispensers, may be incorporated in a modular work station including a closed storage and supply container for the primer compound and a solvent flush system for cleaning hoses and fluid dispenser of the reaction priming resins. The fluid dispenser may also be mounted upon an oscillating carriage whereby in one position of the carriage, spent applicator tips are removed and replaced by new tips by a loader, and in another position the marginal edges of glazing units are moved through the applicator tips by a robot arm for application of a band of the priming compound.
The operational design consists of a column or post-like structure that houses a shaft that rotates or indexes in this structure. Two arms that are positioned 90xc2x0 apart are mounted on the top of the shaft. At the end of these two arms, a fluid dispenser is mounted to a compliance fixture. Two cantilevered beams are attached to the column housing in spaced apart and parallel relationship to the rotating arms. Upon these beams are mounted articulated fixtures to remove spent applicator tips from the fluid dispenser and then reattach a new applicator tip.
The object upon which the fluid is to be applied is usually on a robot. The object is then moved by the robot relative to the fluid dispenser to apply the fluid coating to the desired areas on the object. Devices other than a robot can also be used to provide the movement of the object during the fluid application process.
The design and the unique operational programmable functions, provide precision liquid lay down on glass and other products in a controlled and rapid automatic production cycle. This design with the employment of two fluid applicators on separate indexing arms provides many advantages such as:
1. The ability to apply, with precision, fluid primers that consist of two liquid products that must be applied in precise band width, volume, mil thickness, sequence, etc.;
2. The ability to use the same liquid within both fluid dispensers, but employ different applicator tips to give variable lay down;
3. A means to clean the surface before the lay down of primer, activator, adhesives, etc.;
4. The ability to use any combination of two pairs of applicators and any combination of two liquids; and
5. The unit can be used with only one arm and applicator tip.
In the process to apply primers, adhesives, promoters, etc. to automotive glass and like application, it is necessary to maneuver the specialized tip applicators into many angular modes to provide constant regulated pressure contact with the glass. It is also necessary to maintain band width coverage on all designated surfaces and at the same time control the mil thickness of the fluid that is applied to meet the required quality standards.
There are many applications where the design of the product demands a non-uniform and constant changing band width on one or two edges or on one or both sides of the light and/or a mixture of these variables on a single piece of glass. To accomplish such requirements, it is frequently necessary to employ two different applicator tip designs. On one portion of the product, it may be necessary to have a vertical placement of the applicator tip with respect to the product. On another section of the product, it may be necessary to use the applicator tip in a horizontal mode. Many design factors of the product dictate the ability or inability to perform the required liquid lay down in one automated cycle.
The capability to perform this type of complex pattern for liquid application in a rapid, single automatic cycle has been accomplished with the design of the compliance mechanism that can rotate within its mounting to position the fluid dispenser in either a vertical or horizontal position or an angular position between vertical and horizontal.
It is accordingly an object of the invention to provide a device for applying a uniform band of primer material to selected peripheral marginal areas of a sheet member.
Another object of the invention is to provide such a device which minimizes waste of the primer or adhesion promoting material.
Another object of the invention is to provide such a device which is adapted to apply a primer material along the peripheral margin of either or both major surfaces of the sheet member, the edges thereof, and the interior peripheral margins of a pair of spaced sheet members.
Another object of the invention is to provide a device and system of operation where different fluids can be applied to the object that is to be coated and the fluids are applied in a predetermined sequential manner.
Still another object of the invention is to provide such a device requiring a minimum of manual labor in its operation.
Yet another object of the invention is to provide such a device utilizing a closed supply system so as to minimize escape of solvent materials at the work station and entry of moisture to sensitive reactive fluids.
Another object is to provide precision metering to maintain set parameters of material usage.
Other objects and advantages of the present invention will become apparent to those skilled in the art upon a review of the following detailed description of the preferred embodiments and the accompanying drawings.